And now for something …

Tricky tricky! A few ways to do it …

If full SQL installed

Use if full SQL is installed, or if you installed SQL 2008 with Visual Studio.

1. Install Windows Powershell if you do not have it.
2. Download the setup file of “SQL Server 2008 Express with Tools” or “SQL Server 2008 Express with Advanced Services.”
   • SQL Server 2008 Express with Tools – http://www.microsoft.com/downloads/details.aspx?FamilyId=7522A683-4CB2-454E-B908-E805E9BD4E28&displaylang=en
   • SQL Server 2008 Express with Advanced Services – http://www.microsoft.com/downloads/details.aspx?FamilyId=B5D1B8C3-FDA5-4508-B0D0-1311D670E336&displaylang=en
3. Execute the setup file to open SQL Server Installation Center, click Installation -> New SQL Server stand-alone installation or add features to an existing installation.
4. Install setup files if prompted.
5. In step Installation Type, choose Add features to an existing instance of SQL Server 2008, select the existing SQL Server 2008 instance name in the dropdown list, press Next to go to step Feature Selection.
6. In step Feature Selection, select the checkbox Management Tools–Basic from Shared Features, and then press Next and finish the rest steps of the installation.

Referenced from: http://forums.asp.net/p/1326742/2658582.aspx

If basic SQL installed

Use for client installs, or any installs using the basic (non-developer) version of SQL Express 2008 (which includes some application bootstrappers).

1. Install Windows Powershell if you do not have it.
2. Download SQL Management Studio Express 2008 setup file: http://www.microsoft.com/downloads/details.aspx?FamilyID=08e52ac2-1d62-45f6-9a4a-4b76a8564a2b&displaylang=en
3. Execute the setup file to open SQL Server Installation Center. Click Maintenance -> Edition Upgrade.
4. Install setup support files when prompted.
5. In step Select Instance, select SQLExpress and click Next.
6. In step Edition Upgrade Rules, fix any errors, and click Next.
7. In step Ready to upgrade edition, click Upgrade. The SQL installer will not appear to do anything, and does not have any progress indicator — just sit tight, it is working!
8. When completed, click Close.
9. Go back to SQL Server Installation Center, and click Installation -> New SQL Server stand-alone installation or add features to an existing installation.
10. Install setup support files when prompted.
11. In step Installation Type, select Add features to an existing instance of SQL Server 2008, and select SQLExpress. Click Next.
12. In step Feature Selection, check the box Management Tools–Basic from the Shared Features section. Click Next and finish the installation.

Referenced from: http://msdn.microsoft.com/en-us/library/ms365247.aspx

If none of the above works

1. Go to Add / Remove programs and uninstall Microsoft SQL Server 2008 (leave all other SQL 2008 components intact) and Microsoft SQL Server Management Studio Express.
2. Reboot
3. Download the setup file of “SQL Server 2008 Express with Tools” or “SQL Server 2008 Express with Advanced Services.”
   • SQL Server 2008 Express with Tools – http://www.microsoft.com/downloads/details.aspx?FamilyId=7522A683-4CB2-454E-B908-E805E9BD4E28&displaylang=en
   • SQL Server 2008 Express with Advanced Services – http://www.microsoft.com/downloads/details.aspx?FamilyId=B5D1B8C3-FDA5-4508-B0D0-1311D670E336&displaylang=en
4. Execute the setup file to open SQL Server Installation Center, and click Installation -> New SQL Server stand-alone installation or add features to an existing installation.
5. Install setup support files when prompted.
6. Check the checkbox for Database Engine Servers from the Instance Features section, and Management Tools–Basic from the Shared Features section. Click Next.
7. In step Instance Configuration:
   • Select Named instance and name it SQLExpress.
   • Set Instance ID = SQLExpress
   • Set Instance root directory = C:\Program Files\Microsoft SQL Server\.
   • Click Next.
8. In step Server Configuration:
   • Set SQL Server Database Engine Account Name = NT Authority\SYSTEM
   • Set Start Type = Automatic.
   • Set SQL Server Browser Account Name = NT Authority\SYSTEM
   • Set Start Type = Automatic. Click Next.
9. In step Database Engine Configuration:
   • Set Authentication mode = Windows authentication mode.
   • From Specify SQL Server administrators section, click Add and add System user. Click Next.
10. Correct any errors and finish installation.

If none of the above works for real

1. Go to START and type CMD.
2. Type: format C:
3. Go have a beer.  Or three.  Or just finish that bottle of gin.

Referenced from: a support call with Microsoft